CHEM 2條mole 數

[匿名]

2012-02-13 3:28 am

1. 1.200g of a compound containing only carbon, hydrogen and oxygen gave 1.173g of carbon dioxide and 0.240g of water on complete combustion. Find the empirical formula of the compound.

2. A compund has the empirical formula CxHy. On the analysis, 1.000g of the compound is found to contain 0.857g of carbon. Find the values of x and y.

回答 (1)

不用客氣

2012-02-13 7:01 pm

✔ 最佳答案

1.
Mass fraction of H in H2O = 1x2/(1x2 + 16) = 2/18
Mass fraction of C in CO2 = 12/(12 + 16x2) = 12/44

In 1.200 g of the compound :
Mass of C = 1.173 x (12/44) = 0.3199 g
Mass of H = 0.240 x (2/18) = 0.0267 g
Mass of O = 1.200 - (0.3199 + 0.0267) = 0.8534

Mole ratio C :H : O
= 0.3199/12 : 0.0267/1 : 0.8534/16
= 0.0267 : 0.0267 : 0.0533
= 1 : 1 : 2

Hence, empirical formula of the compound = CHO2

= = = = =
2.
Mole ratio C : H
= 0.857/12 : (1 - 0.857)/1
= 0.0714 : 0.143
= 1 : 2

Hence, x = 1 and y = 2

參考: micatkie

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